/****************************************************************************
 * arch/arm/src/stm32/stm32_adc.c
 *
 *   Copyright (C) 2011, 2013 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *           Diego Sanchez <dsanchez@nx-engineering.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdio.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <semaphore.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <unistd.h>

#include <arch/board/board.h>
#include <nuttx/arch.h>
#include <nuttx/analog/adc.h>

#include "up_internal.h"
#include "up_arch.h"

#include "chip.h"
#include "stm32.h"
#include "stm32_adc.h"

/* ADC "upper half" support must be enabled */

#ifdef CONFIG_ADC

/* Some ADC peripheral must be enabled */

#if defined(CONFIG_STM32_ADC1) || defined(CONFIG_STM32_ADC2) || defined(CONFIG_STM32_ADC3)

/* This implementation is for the STM32 F1, F2, and F4 only */

#if defined(CONFIG_STM32_STM32F10XX) || defined(CONFIG_STM32_STM32F20XX) || \
    defined(CONFIG_STM32_STM32F40XX)

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/
/* ADC interrupts ***********************************************************/

#ifdef CONFIG_STM32_STM32F10XX
#  define ADC_SR_ALLINTS (ADC_SR_AWD | ADC_SR_EOC | ADC_SR_JEOC)
#else
#  define ADC_SR_ALLINTS (ADC_SR_AWD | ADC_SR_EOC | ADC_SR_JEOC | ADC_SR_OVR)
#endif

#ifdef CONFIG_STM32_STM32F10XX
#  define ADC_CR1_ALLINTS (ADC_CR1_AWDIE | ADC_CR1_EOCIE | ADC_CR1_JEOCIE)
#else
#  define ADC_CR1_ALLINTS (ADC_CR1_AWDIE | ADC_CR1_EOCIE | ADC_CR1_JEOCIE | ADC_CR1_OVRIE)
#endif

/* The maximum number of channels that can be sampled.  If dma support is
 * not enabled, then only a single channel can be sampled.  Otherwise,
 * data overruns would occur.
 */

#ifdef CONFIG_ADC_DMA
#  define ADC_MAX_SAMPLES 16
#else
#  define ADC_MAX_SAMPLES 1
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* This structure describes the state of one ADC block */

struct stm32_dev_s
{
  uint8_t  irq;       /* Interrupt generated by this ADC block */
  uint8_t  nchannels; /* Number of channels */
  uint8_t  intf;      /* ADC interface number */
  uint8_t  current;   /* Current ADC channel being converted */
#ifdef ADC_HAVE_TIMER
  uint8_t  trigger;   /* Timer trigger channel: 0=CC1, 1=CC2, 2=CC3, 3=CC4, 4=TRGO */
#endif
  xcpt_t   isr;       /* Interrupt handler for this ADC block */
  uint32_t base;      /* Base address of registers unique to this ADC block */
#ifdef ADC_HAVE_TIMER
  uint32_t tbase;     /* Base address of timer used by this ADC block */
  uint32_t extsel;    /* EXTSEL value used by this ADC block */
  uint32_t pclck;     /* The PCLK frequency that drives this timer */
  uint32_t freq;      /* The desired frequency of conversions */
#endif
  uint8_t  chanlist[ADC_MAX_SAMPLES];
};

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/* ADC Register access */

static uint32_t adc_getreg(struct stm32_dev_s *priv, int offset);
static void adc_putreg(struct stm32_dev_s *priv, int offset, uint32_t value);
#ifdef ADC_HAVE_TIMER
static uint16_t tim_getreg(struct stm32_dev_s *priv, int offset);
static void tim_putreg(struct stm32_dev_s *priv, int offset, uint16_t value);
static void adc_tim_dumpregs(struct stm32_dev_s *priv, FAR const char *msg);
#endif
static void adc_rccreset(struct stm32_dev_s *priv, bool reset);

/* ADC Interrupt Handler */

static int adc_interrupt(FAR struct adc_dev_s *dev);
#if defined(CONFIG_STM32_STM32F10XX) && (defined(CONFIG_STM32_ADC1) || defined(CONFIG_STM32_ADC2))
static int adc12_interrupt(int irq, void *context);
#endif
#if defined(CONFIG_STM32_STM32F10XX) && defined (CONFIG_STM32_ADC3)
static int adc3_interrupt(int irq, void *context);
#endif
#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
static int adc123_interrupt(int irq, void *context);
#endif

/* ADC Driver Methods */

static void adc_reset(FAR struct adc_dev_s *dev);
static int  adc_setup(FAR struct adc_dev_s *dev);
static void adc_shutdown(FAR struct adc_dev_s *dev);
static void adc_rxint(FAR struct adc_dev_s *dev, bool enable);
static int  adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg);
static void adc_enable(FAR struct stm32_dev_s *priv, bool enable);

#ifdef ADC_HAVE_TIMER
static void adc_timstart(FAR struct stm32_dev_s *priv, bool enable);
static int  adc_timinit(FAR struct stm32_dev_s *priv);
#endif

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
static void adc_startconv(FAR struct stm32_dev_s *priv, bool enable);
#endif

/****************************************************************************
 * Private Data
 ****************************************************************************/

/* ADC interface operations */

static const struct adc_ops_s g_adcops =
{
  .ao_reset    = adc_reset,
  .ao_setup    = adc_setup,
  .ao_shutdown = adc_shutdown,
  .ao_rxint    = adc_rxint,
  .ao_ioctl    = adc_ioctl,
};

/* ADC1 state */

#ifdef CONFIG_STM32_ADC1
static struct stm32_dev_s g_adcpriv1 =
{
#ifdef CONFIG_STM32_STM32F10XX
  .irq         = STM32_IRQ_ADC12,
  .isr         = adc12_interrupt,
#else
  .irq         = STM32_IRQ_ADC,
  .isr         = adc123_interrupt,
#endif
  .intf        = 1,
  .base        = STM32_ADC1_BASE,
#ifdef ADC1_HAVE_TIMER
  .trigger     = CONFIG_STM32_ADC1_TIMTRIG,
  .tbase       = ADC1_TIMER_BASE,
  .extsel      = ADC1_EXTSEL_VALUE,
  .pclck       = ADC1_TIMER_PCLK_FREQUENCY,
  .freq        = CONFIG_STM32_ADC1_SAMPLE_FREQUENCY,
#endif
};

static struct adc_dev_s g_adcdev1 =
{
  .ad_ops = &g_adcops,
  .ad_priv= &g_adcpriv1,
};
#endif

/* ADC2 state */

#ifdef CONFIG_STM32_ADC2
static struct stm32_dev_s g_adcpriv2 =
{
#ifdef CONFIG_STM32_STM32F10XX
  .irq         = STM32_IRQ_ADC12,
  .isr         = adc12_interrupt,
#else
  .irq         = STM32_IRQ_ADC,
  .isr         = adc123_interrupt,
#endif
  .intf        = 2,
  .base        = STM32_ADC2_BASE,
#ifdef ADC2_HAVE_TIMER
  .trigger     = CONFIG_STM32_ADC2_TIMTRIG,
  .tbase       = ADC2_TIMER_BASE,
  .extsel      = ADC2_EXTSEL_VALUE,
  .pclck       = ADC2_TIMER_PCLK_FREQUENCY,
  .freq        = CONFIG_STM32_ADC2_SAMPLE_FREQUENCY,
#endif
};

static struct adc_dev_s g_adcdev2 =
{
  .ad_ops = &g_adcops,
  .ad_priv= &g_adcpriv2,
};
#endif

/* ADC3 state */

#ifdef CONFIG_STM32_ADC3
static struct stm32_dev_s g_adcpriv3 =
{
#ifdef CONFIG_STM32_STM32F10XX
  .irq         = STM32_IRQ_ADC3,
  .isr         = adc3_interrupt,
#else
  .irq         = STM32_IRQ_ADC,
  .isr         = adc123_interrupt,
#endif
  .intf        = 3,
  .base        = STM32_ADC3_BASE,
#ifdef ADC3_HAVE_TIMER
  .trigger     = CONFIG_STM32_ADC3_TIMTRIG,
  .tbase       = ADC3_TIMER_BASE,
  .extsel      = ADC3_EXTSEL_VALUE,
  .pclck       = ADC3_TIMER_PCLK_FREQUENCY,
  .freq        = CONFIG_STM32_ADC3_SAMPLE_FREQUENCY,
#endif
};

static struct adc_dev_s g_adcdev3 =
{
  .ad_ops = &g_adcops,
  .ad_priv= &g_adcpriv3,
};
#endif

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: adc_getreg
 *
 * Description:
 *   Read the value of an ADC register.
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   offset - The offset to the register to read
 *
 * Returned Value:
 *
 ****************************************************************************/

static uint32_t adc_getreg(struct stm32_dev_s *priv, int offset)
{
  return getreg32(priv->base + offset);
}

/****************************************************************************
 * Name: adc_getreg
 *
 * Description:
 *   Read the value of an ADC register.
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   offset - The offset to the register to read
 *
 * Returned Value:
 *
 ****************************************************************************/

static void adc_putreg(struct stm32_dev_s *priv, int offset, uint32_t value)
{
  putreg32(value, priv->base + offset);
}

/****************************************************************************
 * Name: tim_getreg
 *
 * Description:
 *   Read the value of an ADC timer register.
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   offset - The offset to the register to read
 *
 * Returned Value:
 *   The current contents of the specified register
 *
 ****************************************************************************/

#ifdef ADC_HAVE_TIMER
static uint16_t tim_getreg(struct stm32_dev_s *priv, int offset)
{
  return getreg16(priv->tbase + offset);
}
#endif

/****************************************************************************
 * Name: tim_putreg
 *
 * Description:
 *   Read the value of an ADC timer register.
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   offset - The offset to the register to read
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

#ifdef ADC_HAVE_TIMER
static void tim_putreg(struct stm32_dev_s *priv, int offset, uint16_t value)
{
  putreg16(value, priv->tbase + offset);
}
#endif

/****************************************************************************
 * Name: adc_tim_dumpregs
 *
 * Description:
 *   Dump all timer registers.
 *
 * Input parameters:
 *   priv - A reference to the ADC block status
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

#ifdef ADC_HAVE_TIMER
static void adc_tim_dumpregs(struct stm32_dev_s *priv, FAR const char *msg)
{
#if defined(CONFIG_DEBUG_ANALOG) && defined(CONFIG_DEBUG_VERBOSE)
  avdbg("%s:\n", msg);
  avdbg("  CR1: %04x CR2:  %04x SMCR:  %04x DIER:  %04x\n",
        tim_getreg(priv, STM32_GTIM_CR1_OFFSET),
        tim_getreg(priv, STM32_GTIM_CR2_OFFSET),
        tim_getreg(priv, STM32_GTIM_SMCR_OFFSET),
        tim_getreg(priv, STM32_GTIM_DIER_OFFSET));
  avdbg("   SR: %04x EGR:  0000 CCMR1: %04x CCMR2: %04x\n",
        tim_getreg(priv, STM32_GTIM_SR_OFFSET),
        tim_getreg(priv, STM32_GTIM_CCMR1_OFFSET),
        tim_getreg(priv, STM32_GTIM_CCMR2_OFFSET));
  avdbg(" CCER: %04x CNT:  %04x PSC:   %04x ARR:   %04x\n",
        tim_getreg(priv, STM32_GTIM_CCER_OFFSET),
        tim_getreg(priv, STM32_GTIM_CNT_OFFSET),
        tim_getreg(priv, STM32_GTIM_PSC_OFFSET),
        tim_getreg(priv, STM32_GTIM_ARR_OFFSET));
  avdbg(" CCR1: %04x CCR2: %04x CCR3:  %04x CCR4:  %04x\n",
        tim_getreg(priv, STM32_GTIM_CCR1_OFFSET),
        tim_getreg(priv, STM32_GTIM_CCR2_OFFSET),
        tim_getreg(priv, STM32_GTIM_CCR3_OFFSET),
        tim_getreg(priv, STM32_GTIM_CCR4_OFFSET));

  if (priv->tbase == STM32_TIM1_BASE || priv->tbase == STM32_TIM8_BASE)
    {
      avdbg("  RCR: %04x BDTR: %04x DCR:   %04x DMAR:  %04x\n",
            tim_getreg(priv, STM32_ATIM_RCR_OFFSET),
            tim_getreg(priv, STM32_ATIM_BDTR_OFFSET),
            tim_getreg(priv, STM32_ATIM_DCR_OFFSET),
            tim_getreg(priv, STM32_ATIM_DMAR_OFFSET));
    }
  else
    {
      avdbg("  DCR: %04x DMAR: %04x\n",
            tim_getreg(priv, STM32_GTIM_DCR_OFFSET),
            tim_getreg(priv, STM32_GTIM_DMAR_OFFSET));
    }
#endif
}
#endif

/****************************************************************************
 * Name: adc_timstart
 *
 * Description:
 *   Start (or stop) the timer counter
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   enable - True: Start conversion
 *
 * Returned Value:
 *
 ****************************************************************************/

 #ifdef ADC_HAVE_TIMER
static void adc_timstart(struct stm32_dev_s *priv, bool enable)
{
  uint16_t regval;

  avdbg("enable: %d\n", enable);
  regval  = tim_getreg(priv, STM32_GTIM_CR1_OFFSET);

  if (enable)
    {
      /* Start the counter */

      regval |= ATIM_CR1_CEN;
    }

  else
    {
      /* Disable the counter */

      regval &= ~ATIM_CR1_CEN;
    }
  tim_putreg(priv, STM32_GTIM_CR1_OFFSET, regval);
}
#endif

/****************************************************************************
 * Name: adc_timinit
 *
 * Description:
 *   Initialize the timer that drivers the ADC sampling for this channel using
 *   the pre-calculated timer divider definitions.
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *
 * Returned Value:
 *   Zero on success; a negated errno value on failure.
 *
 ****************************************************************************/

#ifdef ADC_HAVE_TIMER
static int adc_timinit(FAR struct stm32_dev_s *priv)
{
  uint32_t prescaler;
  uint32_t reload;
  uint32_t regval;
  uint32_t timclk;

  uint16_t cr1;
  uint16_t cr2;
  uint16_t ccmr1;
  uint16_t ccmr2;
  uint16_t ocmode1;
  uint16_t ocmode2;
  uint16_t ccenable;
  uint16_t ccer;
  uint16_t egr;

  avdbg("Initializing timers extsel = %d\n", priv->extsel);

  /* If the timer base address is zero, then this ADC was not configured to
   * use a timer.
   */

  regval  = adc_getreg(priv, STM32_ADC_CR2_OFFSET);

#ifdef CONFIG_STM32_STM32F10XX
  if (!priv->tbase)
    {
      /* Configure the ADC to use the selected timer and timer channel as the trigger
       * EXTTRIG: External Trigger Conversion mode for regular channels DISABLE
       */

      regval &= ~ADC_CR2_EXTTRIG;
      adc_putreg(priv, STM32_ADC_CR2_OFFSET, regval);
      return OK;
    }
  else
    {
      regval |= ADC_CR2_EXTTRIG;
    }
#endif

  /* EXTSEL selection: These bits select the external event used to trigger
   * the start of conversion of a regular group.  NOTE:
   *
   * - The position with with of the EXTSEL field varies from one STM32 MCU
   *   to another.
   * - The width of the EXTSEL field varies from one STM3 MCU to another.
   * - The value in priv->extsel is already shifted into the correct bit position.
   */

  regval &= ~ADC_CR2_EXTSEL_MASK;
  regval |= priv->extsel;
  adc_putreg(priv, STM32_ADC_CR2_OFFSET, regval);

  /* Configure the timer channel to drive the ADC */

  /* Caculate optimal values for the timer prescaler and for the timer reload
   * register.  If freq is the desired frequency, then
   *
   *   reload = timclk / freq
   *   reload = (pclck / prescaler) / freq
   *
   * There are many solutions to do this, but the best solution will be the
   * one that has the largest reload value and the smallest prescaler value.
   * That is the solution that should give us the most accuracy in the timer
   * control.  Subject to:
   *
   *   0 <= prescaler  <= 65536
   *   1 <= reload <= 65535
   *
   * So ( prescaler = pclck / 65535 / freq ) would be optimal.
   */

  prescaler = (priv->pclck / priv->freq + 65534) / 65535;

  /* We need to decrement the prescaler value by one, but only, the value does
   * not underflow.
   */

  if (prescaler < 1)
    {
      adbg("WARNING: Prescaler underflowed.\n");
      prescaler = 1;
    }

  /* Check for overflow */

  else if (prescaler > 65536)
    {
      adbg("WARNING: Prescaler overflowed.\n");
      prescaler = 65536;
    }

  timclk = priv->pclck / prescaler;

  reload = timclk / priv->freq;
  if (reload < 1)
    {
      adbg("WARNING: Reload value underflowed.\n");
      reload = 1;
    }
  else if (reload > 65535)
    {
      adbg("WARNING: Reload value overflowed.\n");
      reload = 65535;
    }

  /* Set up the timer CR1 register */

  cr1 = tim_getreg(priv, STM32_GTIM_CR1_OFFSET);

  /* Disable the timer until we get it configured */

  adc_timstart(priv, false);

  /* Select the Counter Mode == count up:
   *
   * ATIM_CR1_EDGE: The counter counts up or down depending on the
   *                direction bit(DIR).
   * ATIM_CR1_DIR: 0: count up, 1: count down
   */

  cr1 &= ~(ATIM_CR1_DIR | ATIM_CR1_CMS_MASK);
  cr1 |= ATIM_CR1_EDGE;

  /* Set the clock division to zero for all */

  cr1 &= ~GTIM_CR1_CKD_MASK;
  tim_putreg(priv, STM32_GTIM_CR1_OFFSET, cr1);

  /* Set the reload and prescaler values */

  tim_putreg(priv, STM32_GTIM_PSC_OFFSET, prescaler-1);
  tim_putreg(priv, STM32_GTIM_ARR_OFFSET, reload);

  /* Clear the advanced timers repitition counter in TIM1 */

  if (priv->tbase == STM32_TIM1_BASE || priv->tbase == STM32_TIM8_BASE)
    {
      tim_putreg(priv, STM32_ATIM_RCR_OFFSET, 0);
      tim_putreg(priv, STM32_ATIM_BDTR_OFFSET, ATIM_BDTR_MOE); /* Check me */
    }

  /* TIMx event generation: Bit 0 UG: Update generation */

  tim_putreg(priv, STM32_GTIM_EGR_OFFSET, ATIM_EGR_UG);

  /* Handle channel specific setup */

  ocmode1 = 0;
  ocmode2 = 0;

   switch (priv->trigger)
    {
      case 0: /* TimerX CC1 event */
        {
          ccenable = ATIM_CCER_CC1E;
          ocmode1  = (ATIM_CCMR_CCS_CCOUT << ATIM_CCMR1_CC1S_SHIFT) |
                     (ATIM_CCMR_MODE_PWM1 << ATIM_CCMR1_OC1M_SHIFT) |
                     ATIM_CCMR1_OC1PE;

          /* Set the event CC1 */

          egr      = ATIM_EGR_CC1G;

          /* Set the duty cycle by writing to the CCR register for this channel */

          tim_putreg(priv, STM32_GTIM_CCR1_OFFSET, (uint16_t)(reload >> 1));
        }
        break;

      case 1: /* TimerX CC2 event */
        {
          ccenable = ATIM_CCER_CC2E;
          ocmode1  = (ATIM_CCMR_CCS_CCOUT << ATIM_CCMR1_CC2S_SHIFT) |
                     (ATIM_CCMR_MODE_PWM1 << ATIM_CCMR1_OC2M_SHIFT) |
                     ATIM_CCMR1_OC2PE;

          /* Set the event CC2 */

          egr      = ATIM_EGR_CC2G;

          /* Set the duty cycle by writing to the CCR register for this channel */

          tim_putreg(priv, STM32_GTIM_CCR2_OFFSET, (uint16_t)(reload >> 1));
        }
        break;

      case 2: /* TimerX CC3 event */
        {
          ccenable = ATIM_CCER_CC3E;
          ocmode2  = (ATIM_CCMR_CCS_CCOUT << ATIM_CCMR2_CC3S_SHIFT) |
                     (ATIM_CCMR_MODE_PWM1 << ATIM_CCMR2_OC3M_SHIFT) |
                     ATIM_CCMR2_OC3PE;

          /* Set the event CC3 */

          egr      = ATIM_EGR_CC3G;

          /* Set the duty cycle by writing to the CCR register for this channel */

          tim_putreg(priv, STM32_GTIM_CCR3_OFFSET, (uint16_t)(reload >> 1));
        }
        break;

      case 3: /* TimerX CC4 event */
        {
          ccenable = ATIM_CCER_CC4E;
          ocmode2  = (ATIM_CCMR_CCS_CCOUT << ATIM_CCMR2_CC4S_SHIFT) |
                     (ATIM_CCMR_MODE_PWM1 << ATIM_CCMR2_OC4M_SHIFT) |
                     ATIM_CCMR2_OC4PE;

          /* Set the event CC4 */

          egr      = ATIM_EGR_CC4G;

          /* Set the duty cycle by writing to the CCR register for this channel */

          tim_putreg(priv, STM32_GTIM_CCR4_OFFSET, (uint16_t)(reload >> 1));
        }
        break;

      case 4: /* TimerX TRGO event */
        {
          /* TODO: TRGO support not yet implemented */
          /* Set the event TRGO */

          ccenable = 0;
          egr      = GTIM_EGR_TG;

          /* Set the duty cycle by writing to the CCR register for this channel */

          tim_putreg(priv, STM32_GTIM_CCR4_OFFSET, (uint16_t)(reload >> 1));
        }
        break;

      default:
        adbg("No such trigger: %d\n", priv->trigger);
        return -EINVAL;
    }

  /* Disable the Channel by resetting the CCxE Bit in the CCER register */

  ccer = tim_getreg(priv, STM32_GTIM_CCER_OFFSET);
  ccer &= ~ccenable;
  tim_putreg(priv, STM32_GTIM_CCER_OFFSET, ccer);

  /* Fetch the CR2, CCMR1, and CCMR2 register (already have cr1 and ccer) */

  cr2   = tim_getreg(priv, STM32_GTIM_CR2_OFFSET);
  ccmr1 = tim_getreg(priv, STM32_GTIM_CCMR1_OFFSET);
  ccmr2 = tim_getreg(priv, STM32_GTIM_CCMR2_OFFSET);

  /* Reset the Output Compare Mode Bits and set the select output compare mode */

  ccmr1 &= ~(ATIM_CCMR1_CC1S_MASK | ATIM_CCMR1_OC1M_MASK | ATIM_CCMR1_OC1PE |
             ATIM_CCMR1_CC2S_MASK | ATIM_CCMR1_OC2M_MASK | ATIM_CCMR1_OC2PE);
  ccmr2 &= ~(ATIM_CCMR2_CC3S_MASK | ATIM_CCMR2_OC3M_MASK | ATIM_CCMR2_OC3PE |
             ATIM_CCMR2_CC4S_MASK | ATIM_CCMR2_OC4M_MASK | ATIM_CCMR2_OC4PE);
  ccmr1 |= ocmode1;
  ccmr2 |= ocmode2;

  /* Reset the output polarity level of all channels (selects high polarity)*/

  ccer &= ~(ATIM_CCER_CC1P | ATIM_CCER_CC2P | ATIM_CCER_CC3P | ATIM_CCER_CC4P);

  /* Enable the output state of the selected channel (only) */

  ccer &= ~(ATIM_CCER_CC1E | ATIM_CCER_CC2E | ATIM_CCER_CC3E | ATIM_CCER_CC4E);
  ccer |= ccenable;

  if (priv->tbase == STM32_TIM1_BASE || priv->tbase == STM32_TIM8_BASE)
    {
      /* Reset output N polarity level, output N state, output compre state,
       * output compare N idle state.
       */
#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
      ccer &= ~(ATIM_CCER_CC1NE | ATIM_CCER_CC1NP | ATIM_CCER_CC2NE | ATIM_CCER_CC2NP |
                ATIM_CCER_CC3NE | ATIM_CCER_CC3NP | ATIM_CCER_CC4NP);
#else
      ccer &= ~(ATIM_CCER_CC1NE | ATIM_CCER_CC1NP | ATIM_CCER_CC2NE | ATIM_CCER_CC2NP |
                ATIM_CCER_CC3NE | ATIM_CCER_CC3NP);
#endif

      /* Reset the output compare and output compare N IDLE State */

      cr2 &= ~(ATIM_CR2_OIS1 | ATIM_CR2_OIS1N | ATIM_CR2_OIS2 | ATIM_CR2_OIS2N |
               ATIM_CR2_OIS3 | ATIM_CR2_OIS3N | ATIM_CR2_OIS4);
    }
#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
  else
    {
      ccer &= ~(GTIM_CCER_CC1NP | GTIM_CCER_CC2NP | GTIM_CCER_CC3NP | GTIM_CCER_CC4NP);
    }
#endif

  /* Save the modified register values */

  tim_putreg(priv, STM32_GTIM_CR2_OFFSET, cr2);
  tim_putreg(priv, STM32_GTIM_CCMR1_OFFSET, ccmr1);
  tim_putreg(priv, STM32_GTIM_CCMR2_OFFSET, ccmr2);
  tim_putreg(priv, STM32_GTIM_CCER_OFFSET, ccer);
  tim_putreg(priv, STM32_GTIM_EGR_OFFSET, egr);

  /* Set the ARR Preload Bit */

  cr1 = tim_getreg(priv, STM32_GTIM_CR1_OFFSET);
  cr1 |= GTIM_CR1_ARPE;
  tim_putreg(priv, STM32_GTIM_CR1_OFFSET, cr1);

  /* Enable the timer counter
   * All but the CEN bit with the default config in CR1
   */

  adc_timstart(priv, true);

  adc_tim_dumpregs(priv, "After starting Timers");

  return OK;
}
#endif

/****************************************************************************
 * Name: adc_startconv
 *
 * Description:
 *   Start (or stop) the ADC conversion process in DMA mode
 *
 * Input Parameters:
 *   priv - A reference to the ADC block status
 *   enable - True: Start conversion
 *
 * Returned Value:
 *
 ****************************************************************************/

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
static void adc_startconv(struct stm32_dev_s *priv, bool enable)
{
  uint32_t regval;

  avdbg("enable: %d\n", enable);

  regval = adc_getreg(priv, STM32_ADC_CR2_OFFSET);
  if (enable)
    {
      /* Start conversion of regular channles */

      regval |= ADC_CR2_SWSTART;
    }
  else
    {
      /* Disable the conversion of regular channels */

      regval &= ~ADC_CR2_SWSTART;
    }
  adc_putreg(priv, STM32_ADC_CR2_OFFSET,regval);
}
#endif

/****************************************************************************
 * Name: adc_rccreset
 *
 * Description:
 *   Deinitializes the ADCx peripheral registers to their default
 *   reset values. It could set all the ADCs configured.
 *
 * Input Parameters:
 *   regaddr - The register to read
 *   reset - Condition, set or reset
 *
 * Returned Value:
 *
 ****************************************************************************/

static void adc_rccreset(struct stm32_dev_s *priv, bool reset)
{
  irqstate_t flags;
  uint32_t regval;
  uint32_t adcbit;

  /* Pick the appropriate bit in the APB2 reset register */

#ifdef CONFIG_STM32_STM32F10XX
  /* For the STM32 F1, there is an individual bit to reset each ADC. */

  switch (priv->intf)
    {
#ifdef CONFIG_STM32_ADC1
      case 1:
        adcbit = RCC_APB2RSTR_ADC1RST;
        break;
#endif
#ifdef CONFIG_STM32_ADC2
      case 2:
        adcbit = RCC_APB2RSTR_ADC2RST;
        break;
#endif
#ifdef CONFIG_STM32_ADC3
      case 3:
        adcbit = RCC_APB2RSTR_ADC3RST;
        break;
#endif
      default:
        return;
    }

#else
  /* For the STM32 F4, there is one common reset for all ADC block.
   * THIS will probably cause some problems!
   */

  adcbit = RCC_APB2RSTR_ADCRST;
#endif

  /* Disable interrupts.  This is necessary because the APB2RTSR register
   * is used by several different drivers.
   */

  flags = irqsave();

  /* Set or clear the selected bit in the APB2 reset register */

  regval = getreg32(STM32_RCC_APB2RSTR);
  if (reset)
    {
      /* Enable  ADC reset state */

      regval |= adcbit;
    }
  else
    {
      /* Release ADC from reset state */

      regval &= ~adcbit;
    }
  putreg32(regval, STM32_RCC_APB2RSTR);
  irqrestore(flags);
}

/*******************************************************************************
 * Name: adc_enable
 *
 * Description    : Enables or disables the specified ADC peripheral.
 *                  Also, starts a conversion when the ADC is not
 *                  triggered by timers
 *
 * Input Parameters:
 *
 *   enable - true:  enable ADC conversion
 *            false: disable ADC conversion
 *
 * Returned Value:
 *
 *******************************************************************************/

static void adc_enable(FAR struct stm32_dev_s *priv, bool enable)
{
  uint32_t regval;

  avdbg("enable: %d\n", enable);

  regval  = adc_getreg(priv, STM32_ADC_CR2_OFFSET);
  if (enable)
    {
      regval |= ADC_CR2_ADON;
    }
  else
    {
      regval &= ~ADC_CR2_ADON;
    }
  adc_putreg(priv, STM32_ADC_CR2_OFFSET, regval);
}

/****************************************************************************
 * Name: adc_reset
 *
 * Description:
 *   Reset the ADC device.  Called early to initialize the hardware. This
 *   is called, before adc_setup() and on error conditions.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static void adc_reset(FAR struct adc_dev_s *dev)
{
  FAR struct stm32_dev_s *priv = (FAR struct stm32_dev_s *)dev->ad_priv;
  irqstate_t flags;
  uint32_t regval;
  int offset;
  int i;
#ifdef ADC_HAVE_TIMER
  int ret;
#endif

  avdbg("intf: ADC%d\n", priv->intf);
  flags = irqsave();

  /* Enable ADC reset state */

  adc_rccreset(priv, true);

  /* Release ADC from reset state */

  adc_rccreset(priv, false);

  /* Initialize the ADC data structures */

  /* Initialize the watchdog high threshold register */

  adc_putreg(priv, STM32_ADC_HTR_OFFSET, 0x00000fff);

  /* Initialize the watchdog low threshold register */

  adc_putreg(priv, STM32_ADC_LTR_OFFSET, 0x00000000);

  /* Initialize the same sample time for each ADC 55.5 cycles
   *
   * During sample cycles channel selection bits must remain unchanged.
   *
   *   000:   1.5 cycles
   *   001:   7.5 cycles
   *   010:  13.5 cycles
   *   011:  28.5 cycles
   *   100:  41.5 cycles
   *   101:  55.5 cycles
   *   110:  71.5 cycles
   *   111: 239.5 cycles
   */

  adc_putreg(priv, STM32_ADC_SMPR1_OFFSET, 0x00b6db6d);
  adc_putreg(priv, STM32_ADC_SMPR2_OFFSET, 0x00b6db6d);

  /* ADC CR1 Configuration */

  regval  = adc_getreg(priv, STM32_ADC_CR1_OFFSET);

  /* Set mode configuration (Independent mode) */

#ifdef CONFIG_STM32_STM32F10XX
  regval |= ADC_CR1_IND;
#endif

  /* Initialize the Analog watchdog enable */

  regval |= ADC_CR1_AWDEN;
  regval |= (priv->chanlist[0] << ADC_CR1_AWDCH_SHIFT);

  /* Enable interrupt flags */

  regval |= ADC_CR1_ALLINTS;

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)

  /* Enable or disable Overrun interrupt */

  regval &= ~ADC_CR1_OVRIE;

  /* Set the resolution of the conversion */

  regval |= ADC_CR1_RES_12BIT;
#endif

  adc_putreg(priv, STM32_ADC_CR1_OFFSET, regval);

  /* ADC CR2 Configuration */

  regval  = adc_getreg(priv, STM32_ADC_CR2_OFFSET);

  /* Clear CONT, continuous mode disable */

  regval &= ~ADC_CR2_CONT;

  /* Set ALIGN (Right = 0) */

  regval &= ~ADC_CR2_ALIGN;

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
  /* External trigger enable for regular channels */

  regval |= ADC_CR2_EXTEN_RISING;
#endif

  adc_putreg(priv, STM32_ADC_CR2_OFFSET, regval);

  /* Configuration of the channel conversions */

  regval = adc_getreg(priv, STM32_ADC_SQR3_OFFSET) & ADC_SQR3_RESERVED;
  for (i = 0, offset = 0; i < priv->nchannels && i < 6; i++, offset += 5)
    {
      regval |= (uint32_t)priv->chanlist[i] << offset;
    }
  adc_putreg(priv, STM32_ADC_SQR3_OFFSET, regval);

  regval = adc_getreg(priv, STM32_ADC_SQR2_OFFSET) & ADC_SQR2_RESERVED;
  for (i = 6, offset = 0; i < priv->nchannels && i < 12; i++, offset += 5)
    {
      regval |= (uint32_t)priv->chanlist[i] << offset;
    }
  adc_putreg(priv, STM32_ADC_SQR2_OFFSET, regval);

  regval = adc_getreg(priv, STM32_ADC_SQR1_OFFSET) & ADC_SQR1_RESERVED;
  for (i = 12, offset = 0; i < priv->nchannels && i < 16; i++, offset += 5)
    {
      regval |= (uint32_t)priv->chanlist[i] << offset;
    }

  /* ADC CCR configuration */

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
  regval  = getreg32(STM32_ADC_CCR);
  regval &= ~(ADC_CCR_MULTI_MASK | ADC_CCR_DELAY_MASK | ADC_CCR_DDS | ADC_CCR_DMA_MASK |
              ADC_CCR_ADCPRE_MASK | ADC_CCR_VBATE | ADC_CCR_TSVREFE);
  regval |=  (ADC_CCR_MULTI_NONE | ADC_CCR_DMA_DISABLED | ADC_CCR_ADCPRE_DIV2);
  putreg32(regval, STM32_ADC_CCR);
#endif

  /* Set the number of conversions */

  DEBUGASSERT(priv->nchannels <= ADC_MAX_SAMPLES);

  regval |= (((uint32_t)priv->nchannels-1) << ADC_SQR1_L_SHIFT);
  adc_putreg(priv, STM32_ADC_SQR1_OFFSET, regval);

  /* Set the channel index of the first conversion */

  priv->current = 0;

  /* Set ADON to wake up the ADC from Power Down state. */

  adc_enable(priv, true);

#ifdef ADC_HAVE_TIMER
  ret = adc_timinit(priv);
  if (ret!=OK)
   {
      adbg("Error initializing the timers\n");
   }
#else
#ifdef CONFIG_STM32_STM32F10XX
  /* Set ADON (Again) to start the conversion.  Only if Timers are not
   * configured as triggers
   */

  adc_enable(priv, true);
#else
  adc_startconv(priv, true);
#endif /* CONFIG_STM32_STM32F10XX */
#endif /* ADC_HAVE_TIMER */

  irqrestore(flags);

  avdbg("SR:   0x%08x CR1:  0x%08x CR2:  0x%08x\n",
        adc_getreg(priv, STM32_ADC_SR_OFFSET),
        adc_getreg(priv, STM32_ADC_CR1_OFFSET),
        adc_getreg(priv, STM32_ADC_CR2_OFFSET));
  avdbg("SQR1: 0x%08x SQR2: 0x%08x SQR3: 0x%08x\n",
        adc_getreg(priv, STM32_ADC_SQR1_OFFSET),
        adc_getreg(priv, STM32_ADC_SQR2_OFFSET),
        adc_getreg(priv, STM32_ADC_SQR3_OFFSET));
#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
  avdbg("CCR:  0x%08x\n",
        getreg32(STM32_ADC_CCR));
#endif
}

/****************************************************************************
 * Name: adc_setup
 *
 * Description:
 *   Configure the ADC. This method is called the first time that the ADC
 *   device is opened.  This will occur when the port is first opened.
 *   This setup includes configuring and attaching ADC interrupts.  Interrupts
 *   are all disabled upon return.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static int adc_setup(FAR struct adc_dev_s *dev)
{
  FAR struct stm32_dev_s *priv = (FAR struct stm32_dev_s *)dev->ad_priv;
  int ret;

  /* Attach the ADC interrupt */

  ret = irq_attach(priv->irq, priv->isr);
  if (ret == OK)
    {
      /* Make sure that the ADC device is in the powered up, reset state */

      adc_reset(dev);

      /* Enable the ADC interrupt */

      avdbg("Enable the ADC interrupt: irq=%d\n", priv->irq);
      up_enable_irq(priv->irq);
    }

  return ret;
}

/****************************************************************************
 * Name: adc_shutdown
 *
 * Description:
 *   Disable the ADC.  This method is called when the ADC device is closed.
 *   This method reverses the operation the setup method.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static void adc_shutdown(FAR struct adc_dev_s *dev)
{
  FAR struct stm32_dev_s *priv = (FAR struct stm32_dev_s *)dev->ad_priv;

  /* Disable ADC interrupts and detach the ADC interrupt handler */

  up_disable_irq(priv->irq);
  irq_detach(priv->irq);

  /* Disable and reset the ADC module */

  adc_rccreset(priv, true);
}

/****************************************************************************
 * Name: adc_rxint
 *
 * Description:
 *   Call to enable or disable RX interrupts.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static void adc_rxint(FAR struct adc_dev_s *dev, bool enable)
{
  FAR struct stm32_dev_s *priv = (FAR struct stm32_dev_s *)dev->ad_priv;
  uint32_t regval;

  avdbg("intf: %d enable: %d\n", priv->intf, enable);

  regval = adc_getreg(priv, STM32_ADC_CR1_OFFSET);
  if (enable)
    {
      /* Enable the end-of-conversion ADC and analog watchdog interrupts */

      regval |= ADC_CR1_ALLINTS;
    }
  else
    {
      /* Disable all ADC interrupts */

      regval &= ~ADC_CR1_ALLINTS;
    }
  adc_putreg(priv, STM32_ADC_CR1_OFFSET, regval);
}

/****************************************************************************
 * Name: adc_ioctl
 *
 * Description:
 *   All ioctl calls will be routed through this method.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static int adc_ioctl(FAR struct adc_dev_s *dev, int cmd, unsigned long arg)
{
  return -ENOTTY;
}

/****************************************************************************
 * Name: adc_interrupt
 *
 * Description:
 *   Common ADC interrupt handler.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

static int adc_interrupt(FAR struct adc_dev_s *dev)
{
  FAR struct stm32_dev_s *priv = (FAR struct stm32_dev_s *)dev->ad_priv;
  uint32_t adcsr;
  int32_t  value;

  /* Identifies the interruption AWD, OVR or EOC */

  adcsr = adc_getreg(priv, STM32_ADC_SR_OFFSET);
  if ((adcsr & ADC_SR_AWD) != 0)
    {
      alldbg("WARNING: Analog Watchdog, Value converted out of range!\n");
    }

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
  if ((adcsr & ADC_SR_OVR) != 0)
    {
      alldbg("WARNING: Overrun has ocurred!\n");
    }
#endif

  /* EOC: End of conversion */

  if ((adcsr & ADC_SR_EOC) != 0)
    {
      /* Read the converted value and clear EOC bit
       * (It is cleared by reading the ADC_DR)
       */

      value  = adc_getreg(priv, STM32_ADC_DR_OFFSET);
      value &= ADC_DR_DATA_MASK;

      /* Give the ADC data to the ADC driver.  adc_receive accepts 3 parameters:
       *
       * 1) The first is the ADC device instance for this ADC block.
       * 2) The second is the channel number for the data, and
       * 3) The third is the converted data for the channel.
       */

      adc_receive(dev, priv->chanlist[priv->current], value);

      /* Set the channel number of the next channel that will complete conversion */

      priv->current++;

      if (priv->current >= priv->nchannels)
        {
          /* Restart the conversion sequence from the beginning */

          priv->current = 0;
        }
    }

  return OK;
}

/****************************************************************************
 * Name: adc12_interrupt
 *
 * Description:
 *   ADC12 interrupt handler for the STM32 F1 family.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

#if defined(CONFIG_STM32_STM32F10XX) && (defined(CONFIG_STM32_ADC1) || defined(CONFIG_STM32_ADC2))
static int adc12_interrupt(int irq, void *context)
{
  uint32_t regval;
  uint32_t pending;

  /* Check for pending ADC1 interrupts */

#ifdef CONFIG_STM32_ADC1
  regval  = getreg32(STM32_ADC1_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev1);
      regval &= ~pending;
      putreg32(regval, STM32_ADC1_SR);
    }
#endif

  /* Check for pending ADC2 interrupts */

#ifdef CONFIG_STM32_ADC2
  regval  = getreg32(STM32_ADC2_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev2);
      regval &= ~pending;
      putreg32(regval, STM32_ADC2_SR);
    }
#endif
  return OK;
}
#endif

/****************************************************************************
 * Name: adc3_interrupt
 *
 * Description:
 *   ADC1/2 interrupt handler for the STM32 F1 family.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

#if defined (CONFIG_STM32_STM32F10XX) && defined (CONFIG_STM32_ADC3)
static int adc3_interrupt(int irq, void *context)
{
  uint32_t regval;
  uint32_t pending;

  /* Check for pending ADC3 interrupts */

  regval  = getreg32(STM32_ADC3_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev3);
      regval &= ~pending;
      putreg32(regval, STM32_ADC3_SR);
    }

  return OK;
}
#endif

/****************************************************************************
 * Name: adc123_interrupt
 *
 * Description:
 *   ADC1/2/3 interrupt handler for the STM32 F4 family.
 *
 * Input Parameters:
 *
 * Returned Value:
 *
 ****************************************************************************/

#if defined(CONFIG_STM32_STM32F20XX) || defined(CONFIG_STM32_STM32F40XX)
static int adc123_interrupt(int irq, void *context)
{
  uint32_t regval;
  uint32_t pending;

  /* Check for pending ADC1 interrupts */

#ifdef CONFIG_STM32_ADC1
  regval  = getreg32(STM32_ADC1_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev1);
      regval &= ~pending;
      putreg32(regval, STM32_ADC1_SR);
    }
#endif

  /* Check for pending ADC2 interrupts */

#ifdef CONFIG_STM32_ADC2
  regval = getreg32(STM32_ADC2_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev2);
      regval &= ~pending;
      putreg32(regval, STM32_ADC2_SR);
    }
#endif

  /* Check for pending ADC3 interrupts */

#ifdef CONFIG_STM32_ADC3
  regval = getreg32(STM32_ADC3_SR);
  pending = regval & ADC_SR_ALLINTS;
  if (pending != 0)
    {
      adc_interrupt(&g_adcdev3);
      regval &= ~pending;
      putreg32(regval, STM32_ADC3_SR);
    }
#endif
  return OK;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: stm32_adcinitialize
 *
 * Description:
 *   Initialize the ADC.
 *
 *   The logic is, save nchannels : # of channels (conversions) in ADC_SQR1_L
 *   Then, take the chanlist array and store it in the SQR Regs,
 *     chanlist[0] -> ADC_SQR3_SQ1
 *     chanlist[1] -> ADC_SQR3_SQ2
 *     ...
 *     chanlist[15]-> ADC_SQR1_SQ16
 *
 *   up to
 *     chanlist[nchannels]
 *
 * Input Parameters:
 *   intf      - Could be {1,2,3} for ADC1, ADC2, or ADC3
 *   chanlist  - The list of channels
 *   nchannels - Number of channels
 *
 * Returned Value:
 *   Valid ADC device structure reference on succcess; a NULL on failure
 *
 ****************************************************************************/

struct adc_dev_s *stm32_adcinitialize(int intf, const uint8_t *chanlist, int nchannels)
{
  FAR struct adc_dev_s   *dev;
  FAR struct stm32_dev_s *priv;

  avdbg("intf: %d nchannels: %d\n", intf, nchannels);

#ifdef CONFIG_STM32_ADC1
  if (intf == 1)
    {
      avdbg("ADC1 Selected\n");
      dev = &g_adcdev1;
    }
  else
#endif
#ifdef CONFIG_STM32_ADC2
  if (intf == 2)
    {
      avdbg("ADC2 Selected\n");
      dev = &g_adcdev2;
    }
  else
#endif
#ifdef CONFIG_STM32_ADC3
  if (intf == 3)
    {
      avdbg("ADC3 Selected\n");
      dev = &g_adcdev3;
    }
  else
#endif
    {
      adbg("No ADC interface defined\n");
      return NULL;
    }

  /* Configure the selected ADC */

  priv = dev->ad_priv;

  DEBUGASSERT(nchannels <= ADC_MAX_SAMPLES);
  priv->nchannels = nchannels;

  memcpy(priv->chanlist, chanlist, nchannels);
  return dev;
}

#endif /* CONFIG_STM32_STM32F10XX || CONFIG_STM32_STM32F20XX || CONFIG_STM32_STM32F40XX */
#endif /* CONFIG_STM32_ADC || CONFIG_STM32_ADC2 || CONFIG_STM32_ADC3 */
#endif /* CONFIG_ADC */
